Efecto de la oxidación térmica en nanoestructuras de TiO2 sobre la nanodureza y resistencia a la corrosión

This article aimed to analyze the effect of the thermal oxidation in the corrosion resistance and the hardness properties of TiO2 nanostructures obtained by the anodizing process in the HF/H3PO4 solution. TiO2 nanostructures on Ti6Al4V obtained by anodizing processes were subjected to thermal oxidation (TO) treatments over a temperature range from 500 ºC to 620 ºC for 2 hours. Surface morphology was evaluated by using scanning electron microscopy; the hardness properties of TiO2 nanostructures were obtained by Nanoindentation measurements using a Berkovich probe with a tip radius of 150 mm. The corrosion behavior of the samples was studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that TiO2 nanostructures, modified by thermal oxidation, increased the surface properties of hardness and corrosion resistance, compared to the substrate, maintaining its mixed or tubular structure. On the other hand, a transformation of nanotubes to nanopores after 600ºC was evidenced, generating significant changes in the mechanical properties of these structures.El objetivo de este artículo es analizar el efecto de oxidación térmica en la resistencia a la corrosión y las propiedades de dureza de nanoestructuras de TiO2 obtenidas por procesos de anodizado en solución de HF/ H3PO4. Las nanoestructuras de TiO2 sobre Ti6Al4V por procesos de anodizado fueron sometidas a tratamiento de oxidación térmica (OT)en un rango de 500 ºC a 620 ºC por dos (2) horas. La morfología superficial fue evaluada mediante microscopia electrónica de barrido; las propiedades de dureza de nanoestructuras de TiO2 fueron obtenidas por medidas de nanoindentación usando una probeta Berkovich de radio 150 mm. El comportamiento a la corrosión de las muestras fue estudiado usando polarización potenciodinámica y espectroscopia de impedancia electroquímica (EIS). Los resultados mostraron que la nanoestructuras de TiO2, modificadas por oxidación térmica, incrementaron las propiedades superficiales de dureza y resistencia a la corrosión, comparadas a las del substrato, manteniendo su estructura mixta o tubular. Además, se evidenció una transformación de nanotubos a nanoporos después de 600 ºC generando cambios significativos en las propiedades mecánicas de estas estructuras

Influence of Surface Modification on Corrosion and Biocompatibility of Titanium Alloys

Titanium alloys enhance the quality and longevity of human life by replacing or treating various parts of the body. However, the aggressive body fluids lead to corrosion and metal ions dissolution. These ions leach to the adjacent tissues and causes adverse reactions. Surface modifications improve corrosion resistance and biological activity. In this investigation, electropolishing, magnetoelectropolishing, titanium coating and hydroxyapatite coating were carried out on commercially pure titanium (CPTi), Ti6Al4V and Ti6Al4V-ELI (Extra Low Interstitials). These surface modifications are known to affect surface chemistry, morphology, wettability, corrosion resistance and biocompatibility of these materials. In vitro cyclic potentiodynamic polarization tests were conducted in phosphate buffer saline in compliance with ASTM standard. The surface morphology, roughness and wettability of these alloys were studied using scanning electron microscope, atomic force microscope and contact angle meter, respectively. Moreover, biocompatibility of titanium alloys was assessed by growing MC3T3 pre-osteoblast cells on the surfaces

Fabrication Of Ti-40Nb-10HA Composite And Ti-40Nb Alloy With Surface Nanotubes For Implant Application

The criteria of today’s biomaterials has included both physical properties and its ability to promote growth of body tissue. In today’s technology, there are two methods to improve bioactivity of the biomaterials are by adding bioactive materials such as hydroxyapatite (HA) and surface modification of the materials. Hence, the mechanical properties and bioactivity of Ti-40Nb-10HA composite was studied and the investigation of the feasibility of forming nanotubes on Ti-40Nb alloy was also conducted. Ti-40Nb-10HA and Ti-40Nb was fabricated by powder metallurgy method with the compaction pressure of 500 MPa. Ti-40Nb-10HA was sintered at variation of temperature (900°C –1300 °C). Mechanical testings’ results show that the densification occurs when the sintering temperature increases. The relative density of the sintered composite increases as sintering temperature increases from 91.54% to 97.09%. The corrosion rates of the sintered Ti-40Nb-10HA composite is within the range of 0.0348 to 0.1494 mm/year. The modulus of the composite increase as the sintering temperature increase from 1000 °C to 1300 °C (17.6 GPa to 20.03 GPa) which is comparable with the modulus of human bone which is 18GPa. The Ti-40Nb-10HA composite sintered at 1100°C to 1300 °C show increasing micro hardness (112.46 HV to 183.85 HV) and compressive strength (159 MPa to 193.33 MPa). In-vivo evaluation in HBSS for 7 days, nucleation and growth of apatite increases as the sintering temperature increases from 1000°C to 1200°C while the surface modification of Ti-Nb (sintered at 1200°C) exhibited formation of oxide nanotube with reducing diameter from 70 nm to 50 nm when volume percentage of NH4F in electrolyte increased from 0.5 vol% to 0.7 vol%

Improvement of osseointegration of Ti–6Al–4V ELI alloy orthodontic mini-screws through anodization, cyclic pre-calcification, and heat treatments

Abstract Background Mini-screws are widely used as temporary anchorages in orthodontic treatment, but have the disadvantage of showing a high failure rate of about 10%. Therefore, orthodontic mini-screws should have high biocompatibility and retention. Previous studies have demonstrated that the retention of mini-screws can be improved by imparting bioactivity to the surface. The method for imparting bioactivity proposed in this paper is to sequentially perform anodization, periodic pre-calcification, and heat treatments with a Ti–6Al–4V ELI alloy mini-screw. Materials and methods A TiO2 nanotube-structured layer was formed on the surface of the Ti–6Al–4V ELI alloy mini-screw through anodization in which a voltage of 20V was applied to a glycerol solution containing 20 wt% H2O and 1.4 wt% NH4F for 60min. Fine granular calcium phosphate precipitates of HA and octacalcium phosphate were generated as clusters on the surface through the cyclic pre-calcification and heat treatments. The cyclic pre-calcification treatment is a process of immersion in a 0.05M NaH2PO4 solution and a saturated Ca(OH)2 solution at 90°C for 1min each. Results It was confirmed that the densely structured protrusions were precipitated, and Ca and P concentrations, which bind and concentrate endogenous bone morphogenetic proteins, increased on the surface after simulated body fluid (SBF) immersion test. In addition, the removal torque of the mini-screw fixed into rabbit tibias for 4weeks was measured to be 8.70 ± 2.60Ncm. Conclusions A noteworthy point in this paper is that the Ca and P concentrations, which provide a scaffold suitable for endogenous bone formation, further increased over time after SBF immersion of the APH group specimens. The other point is that our mini-screws have a significantly higher removal torque compared to untreated mini-screws. These results represent that the mini-screw proposed in this paper can be used as a mini-screw for orthodontics

Corrosion behaviour of Ti6Al4V ELI nanotubes for biomedical applications

[EN] Surfaces engineering on titanium biomedical alloys aiming for improving bone regeneration, healing periods and increasing lifetime needs fora fundamental understanding of the electrochemical reactions occurring at the interface biomaterial/human fluid. There, electrochemical corrosion plays an important role in implant-tissue interaction. The aim of this study is to investigate the effect of different TiO2 surfaces and nanotubes on a Ti6Al4V ELI in their electrochemical corrosion resistance by different electrochemical techniques (open circuit potential, electrochemical impedance spectroscopy, and potentiodynamic polarization). The electrochemical behaviour of native, anodized, nanotubular and annealed nanotubular surfaces were investigated in 1 M NaCl solution. The nanotubular topography was obtained by electrochemical oxidation and the annealing treatment allowed at changing the crystalline structure of the oxides. The nanotube morphology, chemical composition, and structure was studied by Field Emission Scanning Electron Microscopy, Energy Dispersive Spectroscopy, X-ray diffraction and Transmission Electron Microscopy respectively. The results show that the anodic oxidation treatment creates a nanotubular topography that increases the surface area and changes the surface chemical composition. The electrochemical corrosion resistance decreased on the as-formed TiO2 tubes compared to the native oxide layer, due to higher surface area and amorphous crystal structure of the passive film. After annealing treatment, the fluoride ions are eliminated, and nanotubular resistance is enhanced through anatase stabilization.The authors wish to thank the Spanish Ministry of Economy and Competitiveness for the financial support of Research Project MAT2014-53764-C3-1-R, the Generalitat Valenciana for support through PROMETEO 2016/040, and the European Commission via FEDER funds to purchase equipment for research purposes and the Microscopy Service at the Valencia Polytechnic University. Thanks to Alba Dalmau and Javier Navarro Laboulais from Instituto de Seguridad Industrial y Medio Ambiente, Valencia Polytechnic University for the technical assistance with preparation of the electrochemical tests. Thanks to Irene Llorente and Jose Antonio Jimenez from CENIM/CSIC for the technical assistance with XRD characterization.Lario, J.; Viera, M.; Vicente-Escuder, Á.; Igual Muñoz, AN.; Amigó, V. (2019). Corrosion behaviour of Ti6Al4V ELI nanotubes for biomedical applications. Journal of Materials Research and Technology. 8(6):5548-5556. https://doi.org/10.1016/j.jmrt.2019.09.023S554855568

Sol-Gel Derived Hydroxyapatite Coatings for Titanium Implants: a review

With the growing demands for bone implant therapy, titanium (Ti) and its alloys are considered as appropriate choices for the load-bearing bone implant substitutes. However, the interaction of bare Ti-based implants with the tissues is critical to the success of the implants for long-term stability. Thus, surface modifications of Ti implants with biocompatible hydroxyapatite (HAp) coatings before implantation is important and gained interest. Sol-gel is a potential technique for deposition the biocompatible HAp and has many advantages over other methods. Therefore, this review strives to provide widespread overview on the recent development of sol-gel HAp deposition on Ti. This study shows that sol-gel technique was able to produce uniform and homogenous HAp coatings and identified the role of surface pretreatment of Ti substrate, optimizing the sol-gel parameters, substitution, and reinforcement of HAp on improving the coating properties. Critical factors that influence on the characteristics of the deposited sol-gel HAp films as corrosion resistance, adhesion to substrate, bioactivity, morphological, and structural properties are discussed. The review also highlights the critical issues, the most significant challenges, and the areas requiring further research

Recent developments of metallic implants for biomedical applications

Medical implants have undoubtedly made an indelible mark on our world during the last century. More than 100 million humans carry at least one major internal medical device. The prosthesis industry has topped 50 billion US$ in annual sales, with approximately 150 universities throughout the world proposing an undergraduate program in bioengineering or biomedical engineering. Despite that, however, most medical devices have been constructed using a significantly restricted number of conventional metallic, ceramic, polymeric, and composite biomaterials. In this study, recent developments of metallic implants are summarized for biomedical applications. To do this, first desired properties for biomaterials are defined. Then, types of metallic biomaterials are classified as stainless steel, Mg, Co, Ti, nobble and biodegradable ones. After that, surface modifications are defined for corrugation, topographies and chemical modification. Finally, future perspective is outlined for the sake of development new materials as well as production point of view

Corrosion Behavior of Surface-Treated Metallic Implant Materials

Corrosion of taper connections in total hip arthroplasty remains of concern, as particles and ions generated by corrosive processes can cause clinical problems such as periprosthetic osteolysis or adverse reaction to metallic debris. Mechanical surface treatments that introduce compressive residual stresses (RSs) in metallic materials can lead to a better performance in terms of fretting and fatigue and may lower the susceptibility to corrosion. The study investigates the impact of mechanical surface treatments on the corrosion behavior of metallic biomaterials. Compressive RSs were introduced by deep rolling and microblasting in Ti6Al4V and CoCrMo samples. Polished samples served as reference. Corrosion behavior was characterized by repeated anodic polarization. Residual stresses of up to about −900 MPa were introduced by deep rolling with a reach in depth of approximately 500 µm. Microblasting led to compressive RSs up to approximately −800 and −600 MPa for Ti6Al4V and CoCrMo, respectively, in the immediate vicinity of the surface. For Ti6Al4V, microblasting resulted in decreased corrosion resistance with lower breakdown potentials and/or increased passive current densities in comparison to the polished and deep-rolled samples. The corrosion behavior of CoCrMo on the other hand was not affected by the mechanical surface treatments